Any background information described herein is intended to introduce the reader to various aspects of art, which may be related to the present embodiments that are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light.
Many home entertainment devices not only include the capability to communicate with other devices in a home network but also include the ability to receive and/or process available media content from a plurality of sources, including a plurality of providers. The sources and providers may include, but are not limited to, satellite service, cable service, and free to home over the air terrestrial service. The services may operate in the same or different frequency ranges and may use the same or different transmission formats or protocols. The devices for receiving the services often include, but are not limited to, set-top boxes, gateways, televisions, home computers, and the like. Further, many of these devices may include multiple interfaces for different types of externally provided services as well as different types of home networks. These devices may also include additional features internal to the device, such as storage elements, hard drives, compact disk or digital versatile disk drives, and the like.
In order to receive signals from these different services simultaneously, a filtering structure, such as a multiplex filter, is often used to separate the signals. These filtering structures are particularly important if the services operate in separate frequency ranges and/or use separate transmission formats or protocols. For example, a multiplex filter allows the reception of multiple transmission systems, including terrestrial systems complying with Digital Video Broadcasting television standard (DVB-T2) or the Integrated Services Digital Broadcasting television standard (ISDBT) may be included along with reception of satellite signals. A diplex filter, a type of multiplex filter, is often comprised of a high pass filter for a first high frequency band (e.g., a satellite signal frequency band) and a low pass or band pass filter for a second lower frequency band (e.g., a terrestrial or cable broadcast frequency band).
The operation of home entertainment devices are further complicated by the inclusion of home networking functions in the devices. Many of these devices use a home networking system that shares the transmission medium with the incoming transmission system from the service providers. One such example is a multimedia over cable alliance (MoCA) home networking system that operates in a frequency spectrum on the coaxial cable that is unused by the other signal transmission systems.
A system receiving multiple signals from multiple services over a wide range of frequencies creates significant difficulties in creating a suitable diplex or multiplex filter that provides optimal performance for all services. Previous designs often did not require the additional filtering functions to receive certain terrestrial (e.g., DVB-T2 or ISDBT) broadcast signals along with satellite signals on a common coaxial cable input. The design may be further complicated by the inclusion of an interface to a wired home communication network, such as the MoCA network. For example, frequency guard bands between the frequency ranges for the terrestrial and satellite services may be small in frequency range requiring more selectivity from the filter sections. Further, unused frequency bands between the filters in which undesirable characteristics from the filter sections may be tolerated may not be present. Additionally, systems that did include unused frequency ranges and guard bands may still require a high amount of rejection for signals that are in the frequency range outside of the desired frequency range. Filters used in these systems may still not provide sufficient stopband frequency rejection or may introduce undesired frequency anomalies in the passband frequency response due to interaction between filter sections of a diplex or multiplex filter. Therefore, there is a need for a more optimal filtering structure that allows for reception of multiple signals in separate frequency ranges.
The introduction of home networking use for home entertainment devices has also created the use of new home entertainment devices that share content between one or more main devices and simpler terminal devices connected only to the home network. However, although the simpler device only operates with signals on the home network, the impedance from the device as seen on the coaxial cable network must be matched on all operating frequencies including those not used in a simplified product. The simpler devices often use the same filter structure for the multiplex filter but replace the unused signal processing circuits for receiving signals from the transmission systems with a terminating circuit. However, in this approach, the resulting circuitry can be very complex. Therefore, to reduce cost and size, a simpler solution may be desirable.